1. Field of the Invention
The present invention relates to a letter printing method for printing letters using a line thermal head and a ribbon tape.
2. Description of the Prior Art
When letters are printed on a packaging material film, such as a plastic film for packaging purpose, there is often employed a letter printing method using a line thermal head and a ribbon tape. In the letter print on the packaging material film, there are required many kinds of letter prints, including those of a laterally written form, longitudinally written form or the like, according to goods to be packaged. For example, in case of marking a tastable time period, there is a case where a lateral writing is done or a longitudinal writing is done relative to a running direction of the packaging material film in a packaging device according to design of a package or arrangement of an ornamental pattern applied.
On the other hand, while the ribbon tape used for the letter print has usually a width of about 60 mm, in case this ribbon tape is used for printing letters, for example, for printing one line of the tastable time period, longitudinally, only a small part of the widthwise directional portion of the ribbon tape is used and then already the ribbon tape will be wound around a reel which is for winding the ribbon tape after used. The ribbon tape is one of highly expensive consumables and it will be very uneconomical if the ribbon tape is abandoned with only the small part of the entire width having been used.